The disclosed embodiments generally relate to altimeter switches, and in particular, to improvements to traditional mechanically based altimeter switch designs.
An altimeter switch generally measures altitude and provides one or more switch channels with normally open and normally closed switches that change state when a particular altitude is reached. Traditional altitude switch designs for harsh environments are generally mechanical in nature and operate by means of an inflatable bladder or bellows that mechanically depresses a push-button switch as the bladder inflates with altitude. The altitude setpoint is set by mechanically adjusting the distance between the push button switch and the bellows. Variations in the mechanical actions of the push button switch and the bellows results in a loss of accuracy of the setpoint on the order of several thousand feet, forcing engineers to design interfacing systems with an extremely high error tolerance. These types of bladder and mechanical push button switch systems are not only inaccurate, but are relatively large and difficult to manufacture. The traditional systems generally require hand wiring and soldering each sensor assembly resulting in long build times and susceptibility to workmanship and vibration issues. If the altitude setpoint for an application changes, a new push button switch and bellows combination must be assembled and installed in place of the previous combination. Furthermore, these systems are prone to failure under operating conditions in the field, when reliability is most important, for example, when using the altimeter switch to control pyrotechnic firings to separate rocket stages or to release parachutes.
It would be advantageous to provide a more accurate altitude switch that is more reliable, provides similar switch channel density, has easier to reconfigure setpoints and is easier to assemble.